Bee Moth
Aphomia sociella
Identification & Advisory Service
Other names: Wax Moth *
IAS sheet 7
Classification
Class Insecta
Order Lepidoptera
Family Pyralidae
* This name may lead to confusion with the Wax Moth Galleria mellonella or the Lesser Wax Moth Achroia grisella.
Both of them are also called Bee Moths by some apiculturists, so we should stick with the names indicated in bold type.
Identification
Bee Moth males and females are different. Females are 33 mm long, have olive-grey forewings with pinkish central area
and a large and a small black spots. Males are 35 mm long, have more contrasting colours on their forewings, mainly
whitish and brown, with a zigzagging line over the middle. The larvae are yellow, slim caterpillars with large, darker
heads. Nine pairs of dark spiracles (small breathing holes) are well visible on the sides: one on the first thoracic
abdomen and eight on the abdominal segments. Signs of infestation in bumblebee nests: tough silk spun by young
larvae, destroyed cells, and a waxy substance they produce. The cocoons are up to 50 mm long tubes made of very
tough silk strongly attached to the substrate, usually wood. They are stuck together in large numbers.
Female
Male
Infestation
Larva
Cocoons
Distribution and habitat
The Bee Moths are widely distributed in Europe as well as in Britain. They have been introduced to eastern North
America. Adult moths are found in various habitats where the hosts (bumblebees and wasps) make their nests. Females
prefer to lay their eggs in aerial, exposed nests such as those of the Median Wasp Dolichovespula media, or in nests
made up on walls or in nest boxes by the Red-tailed Bumblebee Bombus lapidarius. The nests built close to or under the
ground such as those of the German Wasp Vespula germanica or the Buff-tailed Bumblebee Bombus terrestris are less
sought-after.
The Natural History Museum – Identification and Advisory Service – Cromwell Road, London SW7 5BD U.K. +44 (0)20 7942 5045 [email protected]
The IAS operates in the Angela Marmont Centre for UK Biodiversity. Visit us in the Museum Monday to Friday 10 am to 5:30 pm. www.nhm.ac.uk
Life cycle
The adult moths are nocturnal and can be attracted to light. They fly from June to August. The after mating, the females
search suitable host nests and lay up to 100 eggs there. The young larvae move quickly and protect themselves by
spinning a strong silk. They grow eating nest materials, stored food, their host’s larvae dejections and other wastes.
Older larvae also eat young bumblebee or was larvae. Caterpillars are very active digging tunnels in the combs and
spinning silken webs very dense and difficult to penetrate. The last stage caterpillars move out of the host’s nests and
spin long, tough cocoons in communal masses often between planks of wood or narrow gaps between two adjacent
surfaces. These are very difficult to remove and the webbing has the consistence of soft cloth. The Bee Moths
overwinter as larvae in these structures, then in the spring they pupate to emerge as adults at the beginning of summer.
Damage and control
The caterpillars of the Bee Moth are neither parasitic nor strictly predatory. Since they mostly feed on nest materials and
waste products of the bee and wasp larvae, as well as on dead adults, they are classified as inquilines (animals that live
commensally in the nest, burrow, or dwelling place of other animals). Bee Moths infest various bumblebee and wasp
species nests, but rarely honeybee colonies. The caterpillars destroy parts of the comb, spill and contaminate food, and
eventually may even consume some of the young bumblebee larvae. This can cause the collapse of some bumblebee
colonies, which is a problem mainly for the commercially bred colonies, used to pollinate crops. The exposed bumblebee
nest boxes are especially vulnerable to Bee Moths infestation. However, strong bumblebee colonies are able to survive
the Bee Moth infestation and produce enough young queens that will reproduce next year. The moths usually colonise
the nest towards the end of the bumblebee’s life cycle anyways, so the real impact is normally low. Bee Moths act as a
natural selection factor for their host species, and in turn they are preyed upon and parasitized by other species,
including birds and bats. Thus, they have their role in the balance of nature and shouldn’t be regarded as pests.
Useful web links
A page with photos of male, female and larva, and a distribution map on UK Moths website:
http://ukmoths.org.uk/show.php?bf=1428
The story of an infestation with Bee Moth larvae, with photos and a video:
http://www.nurturing-nature.co.uk/gardening-for-wildlife/bumblebees-and-wax-moths-the-silent-but-deadly-killers-mustsee-video-2/
The Natural History Museum – Identification and Advisory Service – Cromwell Road, London SW7 5BD U.K. +44 (0)20 7942 5045 [email protected]
The IAS operates in the Angela Marmont Centre for UK Biodiversity. Visit us in the Museum Monday to Friday 10 am to 5:30 pm. www.nhm.ac.uk